Venting TempFactor

dH expresses the height difference between the centre of the inlet and outlet openings.

AeffIn is the area of the openings through which outdoor air flows into the thermal zone. The designation AeffIn indicates that there may be a difference between the size of the physical opening and the cross-sectional area of the jet of air. In the case of high speeds and openings with sharp edges the area has to be corrected with a contraction coefficient, frequently in the order of 0.8-0.95.

AeffOut is the area of the openings through which the indoor air flows out of the thermal zone.

Epsilon is the dimensionless factor for correcting the "thermal efficiency" of the venting. If the inlet and outlet openings are positioned in such a way that they short-circuit, the thermal effect on the zone will be greatly reduced compared with full mixing of the incoming air. It can be very difficult to assess the size of the "mixing factor", but experience indicates that it will often be 0.5-0.9.

The calculated temperature factor (TmpFactor) is shown on the right of the dialog box. Each time the Calculate button is pressed a calculation of the temperaure factor is performed using the current values.